//定义懒加载插件
import { useIntersectionObserver } from '@vueuse/core'

export const lazyPlugin = {
  install (app) {
    //懒加载指令逻辑
    //定义全局指令
    app.directive('img-lazy', {
      mounted (el, binding) {
        //el:指令绑定的元素 img
        //binding：binding.value 指令等于号后面绑定的表达式的值 图片url
        console.log(el, binding.value);
        const { stop } = useIntersectionObserver(
          el,
          ([{ isIntersecting }]) => {
            // console.log(isIntersecting);
            if (isIntersecting) {
              //进入视口区域
              el.src = binding.value
              stop()
            }
          },
        )
      }
    })
  }
}